Process for casting of metal from a refining furnace into a ladle



Nov. 4, 1959 GLAESENER 3,476,549 PROCESS FOR CASTING 0F METAL FROM A REFINING FURNACE INTO A LADLE Filed NOV. 28, 1966 ERNEST GLAESENER I v\\ 'E.\"TOR GU Attorney United States Patent 3,476,549 PROCESS FOR CASTING'OF- METAL FROM A REFINING FURNACE INT-0 A LADLE Ernest Glaesener, Dudelange, Luxembourg, assignor to ARBED, Acieries Reuuies de Burbach-Eich-Dudelange,

S.A., Luxembourg, Luxembourg, a corporation of Luxembourg Filed Nov. 28, 1966, Ser. No. 597,462

Claims priority, application Luxembourg, Dec. 7, 1965,

Int. Cl. CZZc 33700,- B22d 11/10 US. (:1. 75-46 1 C laim The present invention relates to a process for casting metal, especially steel, from a refining furnace into a ladle, and is characterised by the feature, that any contact of the cast-metal jet with the surrounding air is prevented.

It is well known that the main object of the steelrefining process lies in obtaining a metal or alloy having a definite chemical composition. It is therefore quite important, that during casting of refined metal or steel no change in the chemical composition of such metal or alloy may occur, and that no contact of the metal with theoxygen of air should take place. The same is true for slag as particles of slag can be carried along with metal when cast. A change in the composition of slag means a disturbance of the equilibrium existing between refined metal and slag and brings about a change in the composition of metal as well.

According to the present invention no contact of the cast metal with the oxygen of air takes place and particles of slag can reach the bottom of the cast metal column, and 63111111611 easily and rapidly rise to the surface of the metal bath and facilitate decantation, since there exists a considerable diflerence between the density of metal and that. of slag.

The present invention therefore concerns a process for casting metal with the object, that practically no change of the composition of the refined metal will take place during casting ,of' 'such metal from the refining furnace into the ladle According to the present invention any access of air to the jet of cast metal is avoided by casting from the refining furnace takes place through a tube fixed to the tap hole of the refining furnace and reaching nearly to the bottom of the ladle used. In this manner, oxy dation of thev metal jet during the casting operation is completely made impossible. Maintenance of the metal composition, as it has beenrealised at the end of the refining operation, is therefore guaranteed during casting into the ladle. No change of composition due to slag carried along with the ,cast metal can occur, since the movement of suchslag particles through liquid metal takes place solely in the absence of air. According to the present invention any disturbance of the equilibrium prevailing at the end of the refining operation is therefore carefully avoided.

According to the present invention there is no formation during casting of non-metallic inclusions, as will occur with known proceses due to oxydation by air of the metal jet and due to slag particles remaining in the metal 3,476,549 Patented Nov. 4, 1969 bath and not rising to the surface layer of slag. According to the present invention the slag particles will first penetrate deep into the metal bath and will then rapidly rise to the surface of the bath, as their lower density much differs from the density of the molten metal. This is of great practical importance, since according to the invention no contamination of the refined metal can happen.

According to the present invention the addition of alloying and deoxydation agents also is carried out with a tube reaching to a certain depth into the metal bath and below its surface layer of slag. This procedure is of great practical advantage, as such additives are often introduced into the ladle containing or being filled with refined metal, as for example liquid term-manganese. In this manner no oxydation or other undesired reaction with air of these additives is permitted. The added agents will immediately and without alteration get in contact with the metal bath to be treated. According to the invention deoxydation can proceed more easily and alloying agents can directly act in their original state without being oxidyzed or otherwise altered with a risk of contamination for the refined metal. No reaction of these additives with the slag can take place, since the tube used for their introduction will reach beneath the surface layer of slag. As a result a better yield of alloy is made possible.

It is further very advantageous according to the present invention to add to the liquid metal relatively light alloying and deoxydation agents, as for example aluminum. According to known practice, additives with lower density will not always penetrate deeply enough into the metal bath and cannot therefor spread uniformly to give, a homogeneous product.

Another important advantage offered by the present invention is the fact that, when phosphoric anhydride is present in the slag, rephosphoration can practically be completely avoided, since there is no disturbance of the existing equilibrium.

The accompanying sole figure of the drawing is a schematic arrangement of a device to be used according to the present invention, in cross-section with the aid of the drawing the following example is given in order to better illustrate the invention.

The metal leaving the refining furnace 1 through tap hole 2 flows through casting tube 3 into the ladle 4 being placed on the transport car 5. The lower part of the casting tube 3 almost reaches the bottom of the ladle and will therefore quickly be immersed into the: liquid-metal bath 7. As soon as the surface of the bath in the ladle has reached a certain height, the tube 6 used for the introduction of alloying and deoxydation agents is plunged through the layer of slag 8 into the metal bath. If relatively heavy agents are to be added, as for example term-manganese in pieces, addition will be directly carried outthrough the tube used as such. In the case of additives with a lower density however, the tube used for their introduction is first closed at its lower end by means of a thin sheet and after having received the additives is plunged to a greater depth into the metal bath and immediately afterwards is slightly drawn back in order to leave the additives at such depth, after the sheet has been melted. When proceeding in this manner, attention is to be paid to make sure that the tube remains immersed beneath the surface layer of slag.

The tube 3 used according to the invention can be made of a refractory material or of metaLAs a metal or metal alloy use can be made either of one being resistant to the bath at the temperature of the fluid metal bath or of one being melted at such temperature. In the latter case the metal has to be chosen in such a manner as to always keep the lower end of the tube beneath the surface of the metal bath in the ladle.

a 3 4 What is claimed is: through said tube beneath the slag layer on the bath 1. A method of casting molten steel'from a refining" previously introduced into said ladle.

furnace containing a bath of the molten steel covered by a slag layer into a casting ladle for transportation away efe ences C ted from said refining furnace, comprising the steps of affix- 5 UNITED STATESKPATENTS ing a downwardly extending air-tight tube of refractory a 1 f 1 if. material in an air-tight manner in registry with a tap 16 hole formed in said furnace below the surface of the bath 2976587 3/1961 c a e T' 1 r of molten steel therein and below the slag layer above aussan 164-133 X said bath, and positioning said tube and said ladle such FOREIGN PATENTS that said tube opens into said ladle close to the bottom 228,418 g 1963 Austria" passing through said tube; and then completing the tapof the ladle and is trained on the bottom thereof; draining molten steel from said furnace through said tube into said DEWAYNE RUTLEDGE, Pf 111131 Y Examlnel' ladle with entrainment of some slag to form a rising bath WHITE, Assistant Examiner of molten steel in said ladle surmounted by a slag layer v accumulated from slag entrained with the molten steel 266 38 ping of the molten steel from said furnace into said ladle 

